A power generation plant such as a combined cycle power generation system generally includes a gas turbine engine, a heat recovery steam generator, and a steam turbine. The gas turbine engine may be coupled with a generator to produce electricity or to drive other types of loads. The hot combustion gases from the gas turbine engine may be introduced into the heat recovery steam generator to generate a flow of steam. The flow of steam in turn may drive the steam turbine. The steam turbine also may be coupled to a generator to produce additional electricity. A co-generation power generation system and the like may operate in a similar manner to produce both electricity and heat.
Minimizing start-up times may improve the availability of the combined cycle power plant and may reduce overall maintenance costs and start-up emissions. Steam turbine start-up, however, may be slow relative to gas turbine start-up. The start-up time of the steam turbine may be limited by thermal stresses caused by temperature gradients between, for example, the rotor core and the blades. As the rotor temperature is increased, higher inlet steam temperatures may be allowed. Gas turbine output, however, may not be allowed to increase until the steam turbine and the internal rotor are heated to a sufficient temperature. Running the gas turbine at such a low output may reduce the overall power generation, may waste fuel, and may cause higher concentrations of emissions.